The present invention relates generally to methods for fabricating radiation-absorbing semiconductor wafers, and more particularly, to methods for fabricating silicon wafers that can absorb radiation and exhibit diodic current-voltage characteristics.
Modern semiconductor circuits are predominantly based on silicon, which can be readily procured at a lower cost than any other semiconductor and can be easily oxidized. Further, a band gap of 1.05 eV renders silicon suitable for detection of visible light and conversion of sunlight into electricity. Silicon, however, has several shortcomings. For example, it is an indirect band-gap material, and hence it is a relatively poor light emitter. In addition, silicon is not particularly suitable for use in detecting radiation having long wavelengths, such as, infrared radiation employed for telecommunications. Although other semiconductor materials are available that can detect long wavelength radiation better than silicon, they are generally more costly and cannot be readily integrated in optoelectronic circuits that are primarily silicon-based.
Hence, there is a need for silicon-based semiconductor structures and wafers with enhanced radiation-absorbing properties, particularly in wavelengths beyond the band-gap of crystalline silicon. There is also a need for such wafers that can be utilized in fabricating photodetectors that exhibit enhanced responsivity in detecting radiation over a wide wavelength range. Further, there is a need for methods of manufacturing such silicon-based wafers.